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Subject[PATCH 3.12 096/175] mm/memory.c: actually remap enough memory
Date
From: Grazvydas Ignotas <notasas@gmail.com>

3.12-stable review patch. If anyone has any objections, please let me know.

===============

commit 9cb12d7b4ccaa976f97ce0c5fd0f1b6a83bc2a75 upstream.

For whatever reason, generic_access_phys() only remaps one page, but
actually allows to access arbitrary size. It's quite easy to trigger
large reads, like printing out large structure with gdb, which leads to a
crash. Fix it by remapping correct size.

Fixes: 28b2ee20c7cb ("access_process_vm device memory infrastructure")
Signed-off-by: Grazvydas Ignotas <notasas@gmail.com>
Cc: Rik van Riel <riel@redhat.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
---
mm/memory.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memory.c b/mm/memory.c
index db2916f5f378..cf05415c25a6 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -4079,7 +4079,7 @@ int generic_access_phys(struct vm_area_struct *vma, unsigned long addr,
if (follow_phys(vma, addr, write, &prot, &phys_addr))
return -EINVAL;

- maddr = ioremap_prot(phys_addr, PAGE_SIZE, prot);
+ maddr = ioremap_prot(phys_addr, PAGE_ALIGN(len + offset), prot);
if (write)
memcpy_toio(maddr + offset, buf, len);
else
--
2.3.0


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